This invention relates to an adaptive predictive encoding and decoding apparatus for predictive encoding and predictive decoding a screen image in which a half-tone is represented by binary signals.
In such a conventional predictive encoding system, as described in, for example, the U.S. Pat. No. 4,144,547 entitled "APPARATUS AND METHOD FOR ENCODING HALFTONE AND LINE COPY DATA" issued to Stoffel, the number of mis-predicted picture elements for each of the predictive error signals produced for a predetermined block are compared and the predictive error signal having the least mis-predicted picture elements is selected. Such a conventional system has the disadvantages that a sufficient prediction effect is not expected in the case where the prediction is changed from one prediction mode to the other, and significant data-compression can not be obtained because it is necessary to use a prediction mode code representative of a selected prediction mode.
It is, therefore, an object of this invention to provide an adaptive predictive encoding and decoding apparatus in which a high prediction effect can be obtained without using a prediction mode code representative of a selected prediction mode.